The present invention relates to a system for sensing cigarette filters, and in particular, relates to a device that detects the existence and defects of an active charcoal filter, and thus the defects of a tow filter.
In general, a cigarette filter comprises an activated charcoal filter portion and a tow filter portion. FIG. 7 illustrates a completed cigarette filter. A common cigarette filter of this type is an active acetate dual filter 6 consisting of an active charcoal filter portion 2 and a tow filter portion 4. The charcoal filter portion 2 is connected to a tobacco rod 30 (see FIG. 2) to form a smoking article such as a cigarette 31, 32, and the tow filter portion 4 faces the mouth end of the cigarette. The active charcoal filter portion 2 is wrapped with a plug wrap 7, and then combined with the tow filter portion 4 by wrapping with an inner paper 8, and the filter 6 is then combined with a tobacco rod by a tipping paper 9 to form a cigarette 30.
FIG. 2 shows the procedure of supplying cigarette filters during the manufacture of cigarettes. As shown at the top of the Figure, a primary cigarette filter unit 20 is supplied. The primary cigarette filter unit 20 comprises four dual cigarette filters connected, i.e., in sequence from left to right as seen in the FIG. 2, there is an active charcoal filter portion 2, a tow filter portion 4, a tow filter portion 4, an active charcoal filter portion 2, an active charcoal filter portion 2, a tow filter portion 4, a tow filter portion 4, and an active charcoal filter portion 2. The primary filter unit 20 is divided by a cutter 16 (see FIGS. 1 and 3) into two secondary filter units 22, 24. The secondary filter units each consist of an active charcoal filter portion 2, a tow filter portion 4, a tow filter portion 4, and an active charcoal filter 2, and are supplied downward (as viewed in FIG. 2) by a conveying device such as a plurality of rotary conveyance drums 12. Each secondary filter unit 22, 24 has an active carbon filter portion 2 at each end. Tobacco rods 30 are attached to both ends of the secondary cigarette filter units 22, 24 by an assembly unit, and then the centre of the tow filter portion 4 located in the secondary filter unit 22, 24 is cut, whereby the finished products 31, 32 of two cigarettes each having a dual filter are produced.
However, during the process of supplying the cigarette filter units, if a jam occurs at a filtermat or a hooper that temporarily stores the filter units, the filter units may be broken or omitted. In fact, filters having defects can be generated during manufacture. In particular, the active carbon filter portions at the ends of the filter units may be broken off, damaged or omitted.
FIGS. 5 and 6 show examples of this. As shown in FIG. 5, during the supply of the filter units, if the charcoal filter portion 2 is broken at one end of the primary cigarette filter unit 20 and then the primary filter unit 20 is moved longitudinally, the cutter 16 cuts at a portion that is away from the centre of the filter unit 20. One of the secondary filter units 22 thus has the length shorter than the other filter unit 24 (the difference in the length is denoted by “A” in FIG. 5). Also, as shown in FIG. 5, the other secondary filter unit 24 has only charcoal filter at the left end and only tow filter at the right end. The final cigarette products 31, 32 are produced by cutting the filter units at the dotted lines. In this example only one non-defective cigarette is produced. Three cigarettes having defective filters are produced, indicated by shading of the tobacco rods 30.
FIG. 6 represent an example in which the charcoal filter portion 2 at the right end is missing from the primary filter unit 20 and hence also from one of the secondary filter units 24 (indicated as “B”). Therefore, one cigarette is produced wherein the charcoal filter portion does not exist, as shown by shading of the tobacco rod 30.
Also, if the charcoal filter portion 2 is broken and shortened, the position of the primary cigarette filter unit 20 may be moved, and it could happen that the length of the charcoal filter portion 2 or the tow filter 4 is changed.
If it happens that the charcoal filter portion is missing in the cigarette filter unit, or the cigarette filter unit is filled with only charcoal filter or only tow filter, or the length of the charcoal filter is changed, the taste of the cigarette varies and the filter does not function properly. Also, it could happen that the charcoal filter is located to be in contact with then mouth of the smoker.
Moreover, since these problems happen inside the cigarette, they cannot be visually seen well from the outside, and they are often undetected. The defects of the filter will damage the reliance of the customer on the products.
Techniques for sensing filters are known, but they have the disadvantage that they cannot detect all the products having defects because they sense only the outside of the filter. Also, known sensing devices have a complex construction.